Lennox 4HP18LT User manual

506470-01 Issue 1007
Save these instructions for future reference
INSTALLATION AND MAINTENANCE INSTRUCTIONS
4HP18LT Series
Split System Heat Pump
ManufacturedBy
AlliedAir Enterprises, Inc.
A Lennox International Inc. Company
215 Metropolitan Drive
West Columbia, SC 29170
TABLE OF CONTENTS
INSTALLATION ....................................................2
CONNECTION DIAGRAM....................................4
START-UP..........................................................13
OPERATION ......................................................18
MAINTENANCE .................................................23
*506470-01*
Page 1
The equipment covered in this manual is to be installed by trained and experienced service
and installation technicians. Improper installation, modification, service, or use can cause
electricalshock,fire,explosion,orotherconditionswhichmaycausepersonalinjury,death,
or property damage. Use appropriate safety gear including safety glasses and gloves
when installing this equipment.
WARNING
Installation and servicing of air conditioning equipment
can be hazardous due to internal refrigerant pressure
andlive electricalcomponents.Onlytrainedandqualified
servicepersonnelshouldinstallorservicethisequipment.
Installationandserviceperformedbyunqualified persons
canresultinpropertydamage,personalinjury, or death.
WARNING
Risk of electrical shock. Disconnect all remote power
supplies before installing or servicing any portion of the
system. Failureto disconnect powersuppliescan result
in property damage, personal injury, or death.
WARNING
Sharp metal edges can cause injury. When installing
the unit, use care to avoid sharp edges.
WARNING

506470-01 Issue 1007
INSTALLATION Inspection of Shipment
Upon receipt of equipment, carefully inspect it for possible
shipping damage. If damage is found, it should be noted on
the carrier’s freight bill. Take special care to examine the
unitinsidethecarton ifthe cartonisdamaged.Anyconcealed
damage discovered should be reported to the last carrier
immediately, preferably in writing, and should include a
request for inspection by the carrier’s agent.
If any damages are discovered and reported to the carrier
DO NOT INSTALL THE UNIT, as claim may be denied.
Check the unit rating plate to confirm specifications are
as ordered.
Location of Unit
Outdoor units operate under a wide range of weather
conditions; therefore, multiple factors must be considered
when positioning the unit. The unit must be positioned to
giveadequate clearances forsufficientairflowandservicing.
Refer to Figure 1 for installation clearances.
General
Read this entire instruction manual, as well as the
instructions supplied in separate equipment, before
starting the installation. Observe and follow all
warnings, cautions, instructional labels, and tags.
Failure to comply with these instructions could result
in an unsafe condition and/or premature component
failure.
These instructions are intended as a general guide only for
usebyqualifiedpersonnelanddonotsupersedeanynational
or local codes in any way. The installation must comply with
all provincial, state, and local codes as well as the National
ElectricalCode(U.S.)orCanadianElectricalCode(Canada).
Compliance should be determined prior to installation.
4HP18LT condensing units use R410A which is an ozone-
friendly HFC refrigerant. The unit must be installed with a
matching indoor coil and line set. Afilter drier approved for
use with R410Ais installed in the unit.
IMPORTANT: This product has been designed and
manufactured to meet ENERGY STAR criteria for energy
efficiencywhen matched with appropriate coil components.
However, proper refrigerant charge and proper air flow are
critical to achieve rated capacity and efficiency. Installation
of this product should follow the manufacturer’s refrigerant
chargingandairflowinstructions. Failureto confirmproper
charge and airflow may reduce energy efficiency and
shorten equipment life.
Whenservicing or repairingHVAC components,ensure the
fastenersareappropriatelytightened.Table1 shows torque
values for fasteners.
• Place a sound-absorbing material, such as Isomode
underthe unit ifitwillbe installedinalocation or position
that will transmit sound or vibration to the living area or
adjacentbuildings..
Page 2
Figure 1
Installation Clearances
* A service clearance of 30" must be maintained on
one of the sides adjacent to the control box.
Clearance to one of the other three sides must be
36".Clearance tooneof theremainingtwo sidesmay
be 12" and the final side may be 6".
Aclearance of 24" must be maintained between units.
48" clearance required on top of unit. Maximum soffit
overhang is 36".
36” *
36” *
36”
36”
Table 1
Torque Table
Compressor Bolts 90 in. lbs.
#10 Machine Screws 28 in. lbs.
#8 Machine Screws 16 in. lbs.
Sheet Metal Screws 16 in. lbs.
Service Port Caps 8 ft. lbs.
Stem Caps 8 ft. lbs.
Fastener Torque

506470-01 Issue 1007
Roof Mounting
Install unit at a minimum of 6” above surface of the roof to
avoid ice buildup around the unit. Locate the unit above a
load bearing wall or area of the roof that can adequately
supportthe unit. Consultlocalcodesforrooftopapplications.
• Install the unit high enough above the ground or roof to
allow adequate drainage of defrost water and prevent
ice buildup.
• Inheavy snowareas,donotlocate theunitwheredrifting
snowwill occur. The unitbaseshouldbeelevated above
the depth of average snows.
NOTE: Elevation of the unit may be accomplished by
construction a frame using suitable materials. If a
support frame is constructed, it must not block drain
holes in unit base.
• Wheninstalledin areaswherelowambienttemperatures
exist, locate unit so winter prevailing winds do not blow
directly into outdoor coil.
• Locate unit away from overhanging roof lines which
would allow water or ice to drop on, or in front of, coil or
into unit.
Slab Mounting
When installing a unit at grade level, install on slab high
enough above grade so that water from higher ground will
notcollectaround the unit (See Figure 2). Slabshouldhave
a slope tolerance away from the building of 2° or 2” per 5’.
Thiswill prevent ice from building up under the unit during a
defrost cycle. Refer to following roof mounting section for
barrierconstructionif unit must face prevailingwinterwinds.
If unit coil cannot be mounted away from prevailing winter
winds, a wind barrier should be constructed (See Figure 3).
Size the barrier at least the same height and width as the
outdoor unit. Mount barrier 24” from the sides of the unit in
the direction of the prevailing winds.
Electrical Wiring
Allfieldwiring must be done inaccordancewiththe National
Electrical Code (NEC) recommendations, Canadian
Electrical Code (CEC) and CSA Standards, or local codes,
whereapplicable.
Refer to the furnace or blower coil installation instructions
for additional wiring application diagrams and refer to unit
rating plate for minimum circuit ampacity and maximum
overcurrent protection size.
Page 3
Line voltage is present at all components when unit is
not in operation on units with single pole contactors.
Disconnect all remote electric power supplies before
opening access panel. Unit may have multiple power
supplies. Failure to disconnect all power supplies could
result in personal injury or death.
WARNING
Unit must be grounded in accordance with national and
local codes. Failure to ground unit properly can result in
personal injury or death.
WARNING
Figure 2
Figure 3
Slab Mounting
Discharge Air
Mounting Slab
Ground Level
Building
Structure

506470-01 Issue 1007
1.Installlinevoltagepowersupply tounitfromaproperly
sized disconnect switch. Any excess high voltage field
wiringshould be trimmed or secured away from the low
voltage field wiring.
2. Ground unit at unit disconnect switch or to an earth
ground. To facilitate conduit, a hole is in the bottom of
the control box. Connect conduit to the control box
using a proper conduit fitting. Units are approved for
use only with copper conductors. 24V Class II circuit
connections are made in the low voltage junction box.
Refer to Figure 4 for high voltage field wiring diagram.
Acompleteunitwiring diagram is located inside the unit
control box cover.
3. Install room thermostat on an inside wall that is not
subjecttodrafts, direct sunshine, or other heatsources.
4. Install low voltage wiring from outdoor to indoor unit
andfromthermostatto indoor unit. (SeeWireDiagram
on page 27.)
5. Do not bundle any excess 24V control wire inside
control box. Run control wire through installed wire tie
and tighten wire tie to provide low voltage strain relief
andto maintainseperation of field-installedlow andhigh
voltage circuits.
Refrigerant Piping
If the 4HP18LT unit is being installed with a new indoor coil
and line set, the refrigerant connections should be made as
outlined in this section. If an existing line set and/or indoor
coilwillbeused to complete the system, refer to this section
as well as the section that follows entitled - Flushing
Existing Line Set and Indoor Coil.
If this unit is being matched with an approved line set or
indoor coil which was previously charged with R-22
refrigerant, the line set and coil must be flushed prior to
installation. Ifthe unit is being used with and existingindoor
coilwhich was equipped with a liquid linewhich served asa
meteringdevice (RFCI),theliquid linemustbe replacedprior
to the installation of the 4HP18LT unit.
Field refrigerant piping consists of liquid and suction lines
from the outdoor unit (sweat connections) to the indoor coil
(flare or sweat connections).
Select line set diameters from Table 2 to ensure that oil
returns to the compressor. Size vertical suction riser to
maintain minimum velocity at minimum capacity.
Recommended line length is 50’ or less. If more than 50’
line set is required, contact Technical Services. Table 2
showsthediameters for linesetsup to 100’althoughvertical
lift applications and trapping requirements need to be
reviewed with Technical Services for line sets over 50’.
Installing Refrigerant Line
During the installation of an air conditioning system, it is
important to properly isolate the refrigerant line to prevent
unnecessary vibration. Line set contact with the structure
(wall, ceiling, or floor) may cause objectionable noise when
vibration is translated into sound. As a result, more energy
or vibration can be expected. Close attention to line set
isolation must be observed.
Following are some points to consider when placing and
installing a high-efficiency outdoor unit:
Page 4
Figure 4

506470-01 Issue 1007
Placement
Beaware thatsome localitiesareadoptingsoundordinances
based on how noisy the unit is at the neighbor’s home, not
at the original installation. Install the unit as far as possible
fromthepropertyline. Whenpossible, do not install theunit
directly outside a bedroom window. Glass has a verry high
level of sound transmission. Figure 5 shows how to place
the outdoor unit and line set to reduce line set vibration.
Line Set Isolation
Illustrationson pages6and 7demonstrate procedureswhich
ensure proper refrigerant line set isolation. Figure 6 shows
how to install line sets on horizontal runs. Figure 7 shows
how to make a transition from horizontal to vertical. Figure
8 shows how to install line sets on vertical runs.
Brazing Connection Procedure
1. Cut ends of refrigerant lines square (free from nicks or
dents). Debur the ends. The pipe must remain round; do
not pinch end of line.
2. Before making line set connections, use dry nitrogen to
purge the refrigerant piping. This will help to prevent oxida-
tion and the introduction of moisture into the system.
3. Use silver alloy brazing rods (5% or 6% silver alloy for
copper-to-copper brazing or 45% silver alloy for copper-to-
brass or copper-to-steel brazing) which are rated for use
withR410Arefrigerant.
4. RemovetheSchradercoreassemblies before brazing to
protect them from damage due to extreme heat. Replace
the cores when brazing is complete.
5. Remove light maroon washers from service valves and
shield light maroon stickers to protect them during brazing.
Wrap a wet cloth around the valve body and copper tube
stub to protect it from heat damage.
Page 5
Table 2
Liquid Line
BTUH Line Set Length and Size
12 f t . 25 ft. 50 ft. 75 ft. 100 ft.
3/8 3/8 3/8 3/8 3/8
24,000
3/8 3/8 3/8 3/8
3/8 3/8 3/8 1/2
36,000
3/8 3/8 3/8 1/2
48,000
60,000 1/2
1/2
1/2
Refrigerant Line Set Diameters (in.)
S uction Line
BTUH Line Set Length and Size
12 f t . 25 ft. 50 ft. 75 ft. 100 ft.
3/4 3/4
24,000 7/8
36,000
7/8
7/8
1-1/8
7/8
7/8
1-1/8
48,000
7/87/8
7/8
1-1/8
1-1/8
60,000 1/8 1/8 1-1/8
1-1/8
3/4 3/4
For installations exceeding 50’, contact
Technical Services.
Install unit away
from windows
Two 90° elbows installed in lineset
will reduce lineset vibration
Figure 5
Outside Unit Placement & Installation

506470-01 Issue 1007
6. Brazethelinesettotheservicevalve. Quenchthejoints
with water or a wet cloth to prevent heat damage to the
valve core and opening port. The tube end must stay
bottomed in the fitting during final assembly to ensure
proper seating, sealing, and rigidity.
7. Install the thermal expansion valve which is sold
separately and which is approved for use with R410A
refrigerantin theliquidlineatthe indoorcoil(see Refrigerant
Metering Device on page 9).
Page 6
Whenflushingexistinglinesetand/orindoorcoil,besureto
empty all existing traps. Residual mineral oil can act as an
insulator, preventing proper heat transfer. It can also clog
thethermalexpansionvalve,reducingsystemperformance
andcapacity. Failureto properly flushsystemas explained
intheseinstructions will void warranty.
CAUTION
To hang line set from joist or rafter,
use either metal strapping material
or anchored heavy nylon wire ties.
Strapping Material
(around vapor line only)
8’
8’
Tape or Wire Tie
Strap the vapor line to the joist or rafter
at 8 intervals then strap the liquid line
to the vapor line.
’
Floor Joist or
Roof Rafter
Metal Sleeve
Floor Joist or Roof Rafter
Tape or Wire Tie
Wire Tie
(around vapor line only)
Figure 6
Refrigerant Line Sets: Installing Horizontal Runs

506470-01 Issue 1007
Figure 8
Page 7
Figure 7
Anchored
Heavy Nylon
Wire Tie
Wall
Stud
Metal Sleeve Vapor Line Wrapped
in Armaflex
–
Liquid Line
Wall
Stud
Automotive
Muffler-Type
Hanger
Strap Liquid
Line to Vapor
Line
Metal Sleeve Vapor Line Wrapped
in Armaflex
–
Liquid Line
Strap Liquid
Line to Vapor
Line
Refrigerant Line Sets: Transition from Vertical to Horizontal
Outside Wall
Wood Block
Between Studs
IMPORTANT: Refrigerant
lines must not contact wall.
Vapor Line Liquid Line
Wire Tie
Inside Wall
Strap
Sleeve
Wire Tie
Wire Tie
Strap
Wood Block
Sleeve
Vapor Line Wrapped
with Armaflex
Liquid Line
Caulk
PVC Pipe Fiberglass
Insulation
Outside Wall
IMPORTANT:
Refrigerant
lines must not
contact structure.
Refrigeraant Line Sets: Installing Vertical Runs (new construction shown)
NOTE: Similar installation practices
should be used if line set is to be
installed on exterior of outside wall.

506470-01 Issue 1007
Flushing Existing Line Set and Indoor Coil
This procedure should not be performed on systems
which contain contaminants, such as compressor burn
out.
Required Euipment
The following equipment is needed to flush the existing line
setandindoor coil (See Figure 9). Two cleanR-22recovery
bottles, an oil-less recovery machine with a “pump down”
feature, and two sets of gauges (one for use with R-22 and
one for use with R410A).
Flushing Procedure
IMPORTANT: The line set and/or indoor coil must be
flushed with at least the same amount of refrigerant that
previously charged the system. Check the charge in the
flushing cylinder before flushing the unit.
1. Remove existing R-22 refrigerant using the appropriate
procedure.
Ifthe existingoutdoorunitisnotequipped withshutoffvalves,
or if the unit is not operational AND the existing R-22
refrigerant will be used to flush the system:
Disconnect all power to the existing outdoor unit. Connect
theexistingunit, a clean recovery cylinder, and therecovery
machine according to the instructions provided with the
recovery machine. Remove all R-22 refrigerant
fromtheexistingsystem. Refer tothegaugesaftershutdown
to confirm that the entire system is completely void of
refrigerant. Disconnecttheliquidandsuctionlinesfromthe
existing outdoor unit.
If the existing outdoor unit is equipped with manual shutoff
valves AND new R-22 refrigerant will be used to flush the
system:
Start the existing R-22 refrigerant system in cooling mode
and close the liquid line valve. Pump all the existing R-22
refrigerant back into the outdoor unit.
(It may be necessary to bypass the low pressure switches
to ensure complete refrigerant evacuation.)
When the low side system pressures reach 0 psig, close
the suction line valve. Disconnect all power to the existing
outdoorunit. Refer to the gauges after shutdowntoconfirm
that the valves are not allowing refrigerant to flow back into
thelow side ofthesystem. Disconnect theliquidandsuction
lines from the existing outdoor unit.
2. Remove the existing outdoor unit. Set the new R410A
unit and follow the brazing connection procedure outlined
previously on this page to make line set connections. Do
not install the R410A thermal expansion valve at this
time.
3. Make low voltage and line voltage connections to the
new outdoor unit. Do not turn on power to the unit or
open the outdoor unit service valves at this time.
Page 8
Figure 9
Flushing Connections

506470-01 Issue 1007
4. RemovertheexistingR-22refrigerantflowcontrolorifice
or thermal expansion valve before continuing with flushing
procedures. R-22flowcontroldevicesarenotapprovedfor
usewith R410A refrigerantandmay preventproperflushing.
Use a field-provided fitting to reconnect the lines.
5. Removethe pressure tapvalve cores fromthe 4HP18LT
units service valves. Connect an R-22 cylinder with clean
refrigerant to the suction service valve. Connect the R-22
gauge set to the liquid line valve and connect a recovery
maching with an empty recovery tank to the gauge set.
6. Set the recovery machine for liquid recovery and start
the recovery machine. Open the gauge set valves to allow
therecoverymachinetopullavacuumontheexistingsystem
line set and indoor coil.
7. Invert the cylinder of clean R-22 and open its valve to
allow liquid refrigerant to flow in to the system through the
suction line valve. Allow the refrigerant to pass from the
cylinderandthroughthelineset and the indoor coil before it
enters the recovery machine.
8. Afterallof theliquid refrigeranthas beenrecovered,switch
the recovery machine to vapor recovery so that all of the R-
22vaporisrecovered. Allow the recovery machine to pulla
vacuum on the sytem.
NOTE: Asinglesystemflushshouldremoveallof themineral
oilfromtheexistingrefrigerantlinesandindoorcoil. Asecond
flushingmaybedone(usingclean refrigerant) if insufficient
amounts of mineral oil were removed during the first flush.
After each system flush, allow the recovery machine to
pulla vacuum onthe systemat the endof theprocedure.
9. Close the valve on the inverted R-22 cylinder and the
gauge set valves. Pump the remaining refrigerant out of
the recovery machine and turn the machine off.
10. Use nitrogen to break the vacuum on the refrigerant
linesandindoor coil before removing therecoverymachine,
gauges, and R-22 refrigerant drum. Re-install pressure tap
valve cores into the 4SHP18LT unit’s service valves.
11. Install the fixed orifice (or thermal expansion valve
approvedforusewithR410A refrigerant) in the liquid line at
the indoor coil.
Refrigerant Metering Device
4HP18LT units are designed for use with TXV systems.
Refertotheappropriatefollowingsectionforinformationon
installing the chosen refrigerant metering device.
An R410A system will not operate properly with an R-22
metering device.
Install the refrigerant metering device as shown in Figure
11. Do not twist cap tubes when loosening thesealnutfrom
the orifice housing. Use wrench to back up the distributor.
Expansion Valve Systems
Expansion valves equipped with Chatleff-type fittings are
available from the manufacturer. See Table 3 for proper
TXV for each unit.
To install an expansion valve (See Figure 10 above):
1. Separatethe distributor assembly and remove thepiston
orifice and used teflon seal. Insert nozzle end of the
expansion valve along with a new teflon seal into the
distributorandtighten to20-30 ft. lbs. Use backup wrench
on all wrench flats. Overtightening will crush the teflon
seal and may cause a leak.
2. Attach liquid line portion of distributor assembly along
with new teflon seal to the inlet of the expansion valve.
Tighten to 20 - 30 ft. lbs. Use backup wrench on all wrench
flats. Overtightening will crush the teflon seal and may
cause a leak.
Page 9
Figure 10
Table 3
MODEL PART NUMBER
4HP18LT- 24
4HP18LT - 36
H4TXV01
H4TXV02
4HP18LT - 48, -60 H4TXV03
TXV Data

506470-01 Issue 1007
3. Connect the external equalizer line to the equalizer port
on the suction line and tighten to 8 ft.lbs.
4. Strap the superheat sensing bulb to the suction header.
If installing an expansion valve on an indoor coil that
previouslyused afixedorifice, besuretoremovethe existing
fixedorifice. Failureto remove a fixedorificewheninstalling
an expansion valve to the indoor coil will result in improper
operation and damage to the system.
Manifold Gauge Set
Manifoldguage sets usedwithsystems charged withR410A
refrigerant must be capable of handling the higher system
operating pressures. The gauges should be rated for use
withpressures1-800onthehighside and a low side of 30”
vacuumto250psiwithdampenedspeed to 500 psi. Gauge
hoses must be rated for use at up to 800 psi of pressure
with a 4000 psi burst rating.
Liquid and Suction Line Service Valves
The liquid line and suction line service valves (See Figure
11) and service ports are used for leak teating, evacuation,
charging, and checking charge.
Each valve is equipped with a service port which has a
factory-installedSchradervalve. Aserviceportcap protects
the Schrader valve from contamination and serves as the
primary leak seal.
To Access the Schrader Port:
1. Remove the service port cap with an adjustable wrench.
2. Connect gauge to the service port.
3. When testing is completed, replace service port cap.
Tighten finger tight, then an additional 1/6 turn.
To Open Liquid or Suction Line Service Valve:
Remove stem cap with an adjustable wrench.
Use service wrench with a hex-head extension to back the
stem out counterclockwise as far as it will go. Use a 3/16”
hex head extension for liquid line service valves and a 5/
16” extension for suction line service valves.
Replace the stem cap. Tighten finger tight, then tighten an
additional 1/6 turn.
To Close Liquid or Suction Line Service Valve:
1. Remove the stem cap with an adjustable wrench.
2. Use a service wrench with a hex-head extension to turn
the stem clockwise to seat the valve. Tighten firmly.
3. Replace the stem cap. Tighten finger tight, then tighten
an additional 1/6 turn.
Suction Line (Ball Type) Service Valve
Suctionline(ball type) servicevalvesfunctionthe same way
astheother valves; thedifferenceisintheconstruction (See
Figure 12).
Theball valve is equipped with a service port with a factory-
installed Schrader valve. A service port cap protects the
Schrader valve from contamination and serves as the
primary seal.
Leak Testing
After the line set has been connected to the indoor and
outdoor units, the line set connections and indoor unit must
be checked for leaks.
Page 10
Figure 11

506470-01 Issue 1007
Using an Electronic Leak Detector
1. Connect the high pressure hose of the manifold gauge
set to the suction valve service port. (Normally the high
pressure hose is connected to the liquid line port; however,
connectingit tothesuctionportshelpsto protectthe manifold
gauge set from damage caused by high pressure.)
2. Withbothmanifoldvalves closed, connect the cylinder of
R410A refrigerant. Open the valve on the R410A cylinder
(vaporonly).
3. Open the high pressure side of the manifold to allow
R410A into the line set and indoor unit. Weigh in a trace
amount of R410A. (A trace amount is a maximum of 2 oz.
of refrigerant or 3 lbs. pressure.) Close the valve on the
R410A cylinder and the valve on the high pressure side of
the manifold gauge set. Disconnect the R410Acylinder.
4. Connectacylinderofnitrogenwithapressureregulating
valve to the center port of the manifold gauge set. When
using high pressure gas such as nitrogen for this
purpose, be sure to use a regulator that can control the
pressure down to 1 or 2 psig.
5. Adjust nitrogen pressure to 150 psig. Open the valve on
the high side of the manifold gauge set to pressurize the
line set and the indoor coil.
6. After a short period of time, open a refrigerant port to
makesurethatan adequate amount of refrigerant has been
added for detection (refrigerant requirements will vary with
lenths). Checkall jointsforleaks. PurgenitrogenandR410A
mixture. Correct any leaks and rechecks.
Evacuation
Evacuating the system of noncondensables is critical for
proper operation of the unit. Noncondensables are defined
as any gas that will not condense under temperatures and
pressures present during operation of an air conditioning
system. Noncondensables and water vapor combine with
refrigerantto producesubstancesthat corrodecopperpiping
and compressor parts.
Useathermocoupleorthermistorelectronic vacuum gauge
that is calibrated in microns. Use an instrument that reads
down to 50 microns.
1. Connectthe manifold gauge settothe service valveports
as follows:
• Low pressure gauge to suction line service valve
• High pressure gauge to liquid line service valve.
2. Connect micron gauge.
3. Connect the vacuum pump (with vacuum gauge) to the
center port of the manifold gauge set.
Never useoxygento pressurize refrigerationorair con-
ditioningsystems. Oxygenwillexplodeoncontactwith
oil and could cause personal injury or death.
Page 11
Refrigerantcanbeharmful if inhaled. Refrigerant must
always be used and recovered responsibly. Incorrect
orirresponsibleuse of refrigerant can resultinpersonal
injury or death.
WARNING
WARNING
Figure 12
Do Not use a compressor to evacuate a system. Avoid
deep vacuum operation. Extremely low vacuums can
cause internal arcing and compressor failure. Danger
ofequipmentdamage. Damagecausedbydeepvacuum
operation will void warranty.
WARNING

506470-01 Issue 1007
4. Open both manifold valves and start vacuum pump.
5. Evacuate the line set and indoor unit to a minimum of
500microns or lower. During theearlystagesofevacuation,
itis desirable toclosethe manifold gaugevalveatleast once
to determine if there is a rapid rise in pressure. Arapid rise
in pressure indicates a relatively large leak. If this occurs,
the leak testing procedure must be repeated.
6. When 500 microns or lower is maintained, close the
manifold gauge valves, turn off the vacuum pump, and
disconnect the manifold gauge center port hose from the
vacuum pump. Attach the manifold gauge center port hose
toanitrogencylinder with pressure regulator set to 150 psig
and purge the hose. Open the manifold gauge valves to
break the vacuum in the line set and indoor unit. Close the
manifold gauge valves.
7. Shut off the nitrogen cylinder and remove the manifold
gauge hose from the cylinder. Open the manifold gauge
valves to release the nitrogen from the line set and indoor
unit.
8. Reconnect the manifold gauge to the vacuum pump,
turn the pump on, and continue to evacuate the line set and
indoorunit until500microns ismaintainedwithina20 minute
period after shutting off the vacuum pump and closing the
manifold gauge valves.
9. Whenthe requirementsabovehavebeen met,disconnect
themanifold hose fromthevacuum pump. Open theservice
valves to break the vacuum in the line set and indoor unit.
Page 12

506470-01 Issue 1007
START-UP
1. Rotate fan to check for frozen bearings or binding.
2. Inspect all factory and field-installed wiring for loose
connections.
3. Afterevacuation is complete, open liquidlineandsuction
line service valves to release refrigerant charge (contained
in outdoor unit) into system.
4. Replace the stem caps and secure finger tight, then
tighten an additional 1/6 of a turn.
5. Check voltage supply at the disconnect switch. The
voltagemustbewithintherange listedon theunitnameplate.
If not, do not start equipment until the power company has
been consulted and the voltage condition corrected.
6. Set thermostat for cooling demand, turn on power to
indoor blower, and close the outdoor unit disconnect switch
to start the unit.
7. Recheck unit voltage with unit running. Power must be
within range shown on unit nameplate.
Refrigerant Charging
This system is charged with R410A refrigerant which
operates at much higher pressures than R-22. The liquid
line drier provided with the unit is approved for use with
R410A. Do not replace it with one designed for use with R-
22. This unit is NOT approved for use with coils which
use capillary tubes as a refrigerant metering device.
R410A refrigerant cylinders are rose colored.
Refrigerant should be added through the suction valve
in the liquid state.
CertainR410Acylindersare identifiedas beingequipped
with a dip tube. These allow liquid refrigerant to be
drawn from the bottom of the cylinder without inverting
the cylinder. Do not turn this type of cylinder upside
down to draw refrigerant.
Units are factory charged with the amount of R410A
refrigerant indicated on the unit rating plate. This charge is
based on a matching indoor coil and outdoor coil with 15’
line set. For varying lengths of line set, refer to Table 4 for
refrigerant charge adjustment. A blank space is provided
on the unit rating plate to list the actual field charge.
If the system is void of refrigerant, clean the system using
the procedure described below.
1. Use dry nitrogen to pressurized the system and check
for leaks. Repair leaks, if possible.
2. Evacuate the system to remove as much of the moisture
as possible.
3. Use dry nitrogen to break the vacuum.
4. Evacuate the system again.
5. Weightheappropriateamount ofR410Arefrigerant(listed
on unit nameplate) into the system.
6. Monitor the system to determine the amount of moisture
remainingin the oil. Use a test kit to verify that themoisture
content is withing the kit’s dry color range. It may be
necessarytoreplace the filter drier several timestoachieve
the required dryness level. If system dryness is not
verified, the compressor will fail in the future.
The outdoor unit should be charged during warm weather.
However,applicationsarisein which charging must occur in
the colder months. The method of charging is determined
by the unit’s refrigerant metering device and the outdoor
ambient temperature.
Measurethe liquidlinetemperatureand theoutdoorambient
temperature as outlined below:
Page 13
If unit is equipped with a crankcase heater, it should be
energized 24 hours before unit start-up to prevent
compressor damage as a result of slugging.
CAUTION
Mineral oils are not compatible with R410A. If oil must
be added, it must be a polyolester oil.
IMPORTANT
Table 4
3/8 in. 3 oz. Per 5 ft.
Liquid Line Set
Diameter
Oz. per 5 ft. adjust
from 15 ft. line set*
Refrigerant Charge Adjustment
* If line length is greater than 15 ft., add this amount.
If line length is less than 15 ft., remove this amount.

506470-01 Issue 1007
1. Connectthe manifold gauge settothe service valveports
as follows (See Figure 13 above):
• Low pressure gauge to suction line service valve
• High pressure gauge to liquid line service valve
2. Close manifold gauge set valves. Connect the center
manifold hose to an upright cylinder of R410A.
3. If room temperature is below 70°F, set the room
thermostat to call for heat. This will create the necessary
load for properly charging the system in the cooling cycle.
4. Use a digital thermometer to record the outdoor ambient
temperature.
5. Whentheheatingdemandhas been satisfied, switch the
thermostat to cooling mode with a set point of 68°F. When
pressures have stabilized, use a digital thermometer to
record the liquid and suction line temperatures.
6. The outdoor temperature will determine which charging
method to use. Proceed with the appropriate charging
method.
Charge Using Weigh-In Method (Fixed Orifice/TXV
Systems) - Outdoor Temperatures Below 65°F
If the system is void of refrigerant, or if the outdoor ambient
temperature is cool, use the weigh-in method to charge the
unit. Do this after any leaks have been repaired.
1. Recover the refrigerant from the unit.
2. Conduct a leak check, then evacuate as previously
outlined.
3. Weighin the charge according to thetotalamount shown
on the unit nameplate.
If weighing facilities are not available or if unit is being
charged during warm weather, use one of the following
procedures.
Charge Using Subcooling Method (Fixed Orifice/TXV
Systems) - Outdoor Temperatures 65°F or Above
If charging a fixed orifice or TXV system when the outdoor
ambient temperature is 65°F or above, the subcooling
method can be used to charge the unit.
1. With the manifold gauge hose still on the liquid service
portandtheunitoperatingstably, use a digitalthermometer
to check the liquid line temperature. For best results, use
the same digital thermometer to check both the outdoor
ambient and the liquid line temperatures.
2. Atthesametime, record the liquid line pressure reading.
3. Usethetemperature/pressurechart (Table5)todetermine
the saturation temperature for the liquid line pressure
reading.
4. Subtract the liquid line temperature from the saturation
temperature(accordingtothechart)todeterminesubcooling.
Page 14
Figure 13

506470-01 Issue 1007
5. Comparethe subcooling value with those showninTable
7. If subcooling is greater than shown, recover some
refrigerant. If subcooling is less than shown, add some
refrigerant.
ChargeUsingApproach Method (TXV System)- Outdoor
Temperatures 65°F or Above
The following procedure is intended as a general guide and
isforuse on expansionvalve systems only. Forbest results,
indoortemperatureshouldbe 70°F to 80°F. Monitorsystem
pressures while charging.
1. Record outdoor ambient temperature usig a digital
thermometer.
2. Attach high pressure gauge set and operate unit for
several minutes to allow system pressures to stabilize.
3. Comparestabilizedpressureswith thoseprovided inTable
8. Minor variations in these pressures may be expected
due to differences in installations. Significant differences
could mean that the system is not properly charged or
that a problem exists with some component in the
system. Pressures higher than those listed indicate that
thesystemisovercharged. Pressureslowerthanthoselisted
indicate that the system is undercharged. Verify adjusted
charge using the approach method.
4. Use the same digital thermometer to check liquid line
temperature.
5. Subtracttheoutdoor ambient temperature fromtheliquid
line temperture to determine the approach temperature.
Page 15
Table 6
Subcooling Values
Table 5
R410ATemperature/Pressure Chart
Temp.
(F
Pressure
Psig
Temp.
(F
Pressure
Psig
Temp.
(F
Pressure
Psig
32 100.8 74 214.0 116 396.0
33 102.9 75 217.4 117 401.3
34 105.0 76 220.9 118 406.7
35 107.1 77 224.4 119 412.2
36 109.2 78 228.0 120 417.7
37 111.4 79 231.6 121 423.2
38 113.6 80 235.3 122 428.8
39 115.8 81 239.0 123 434.5
40 118.0 82 242.7 124 440.2
41 120.3 83 246.5 125 445.9
42 122.6 84 250.3 126 451.8
43 125.0 85 254.1 127 457.6
44 127.3 86 258.0 128 463.5
45 129.7 87 262.0 129 469.5
46 132.2 88 266.0 130 475.6
47 134.6 89 270.0 131 481.6
48 137.1 90 274.1 132 487.8
49 139.6 91 278.2 133 494.0
50 142.2 92 282.3 134 500.2
51 144.8 93 286.5 135 506.5
52 147.4 94 290.3 136 512.9
53 150.1 95 295.1 137 519.3
54 152.8 96 299.4 138 525.8
55 155.5 97 303.8 139 532.4
56 158.2 98 308.2 140 539.0
57 161.0 99 312.7 141 545.6
58 163.9 100 317.2 142 552.3
59 166.7 101 321.8 143 559.1
60 169.6 102 326.4 144 565.9
61 172.6 103 331.0 145 572.8
62 175.5 104 335.7 146 579.8
63 178.5 105 340.5 147 586.8
64 181.6 106 345.3 148 593.8
65 184.3 107 350.1 149 601.0
66 187.7 108 355.0 150 608.1
67 190.9 109 360.0 151 615.4
68 194.1 110 365.0 152 622.7
69 197.3 111 370.0 153 630.1
70 200.6 112 375.1 154 637.5
71 203.9 113 380.2 155 645.0
72 207.2 114 385.4
73 210.6 115 390.7
72 207.2 114 385.4
73 210.6 115 390.7

506470-01 Issue 1007
=
_
Outdoor Ambient Temperature °F
Liquid Line Temperature °F
Approach Temperature °F
°
°
°
6. Compare the approach value with those shown inTable
9. If the values do not agree with those provided in Table 8,
addrefrigerant tolowerthe approachtemperatureor recover
refrigerant from the system to increase the approach
temperature.
Check Charge Using Normal Operating Pressures
Use Table 7 to perform maintenance checks. Table 7 is not
a procedure for charging the system. Minor variations in
these pressures may be due to differences in installations.
Significant deviations could mean that the system is not
properly charged or that a problem exists with some
component in the system.
Page 16
Table 7
Approach Values for TXV Systems

506470-01 Issue 1007 Page 17
Table 8
L - Liquid S- Suction
Values provided above are typical pressures. Indoor unit matchup, indoor air quality equipment, and indoor
load will case pressures to vary.

506470-01 Issue 1007
OPERATION
Outdoor unit and indoor blower cycle on demand from the
room thermostat. When the thermostat blower switch is
moved to the ON position, the indoor blower operates
continuously.
Filter Drier
Theunitisequipped with a large capacitybi-flowfilterwhich
keepsthesystemcleananddry. Ifreplacementisnecessary,
replace with one of similar design and capacity. The
replacement filter drier must be suitable for use with R410A
refrigerant.
Crankcase Heater
If unit is equipped with a crankcase heater, it should be
energized 24 hours before unit start-up to prevent
compressor damage as a result of slugging.
Emergency Heat Function (Room Thermostat)
An emergency heat function is designed into some room
thermostats. This feature is applicable when isolation of
outdoor unit is required or when auxiliary electric heat is
stage by outdoor thermostats. When the room thermostat
is placed in the emergency heat position, the outdoor unit
control circuit is isolated from power and the field-supplied
relaysbypasstheoutdoorthermostats. Anamber indicating
light simultaneously comes on to remind the homeowner
that the unit is operating in the emergency heat mode.
Emergencyheatisusually usedduring anoutdoorshutdown,
butitshouldalsobeusedfollowingapoweroutageif power
has been off for over an hour and the outdoor temperature
isbelow50°F. Systemshould be left in the emergency heat
modeat least6hourstoallow thecrankcaseheater sufficient
time to prevent compressor slugging.
Defrost System
The defrost system includes two components: the defrost
thermostat and the defrost control.
Defrost Thermostat
The defrost thermostat is located on the liquid line between
the check/expansion valve and the distributor. When the
defrost thermostat senses 42°F or cooler, the thermostat
contactsclose andsendasignal to the defrost controlboard
to start the defrost timing. It also terminates defrost when
the liquid line warms up to 70°F.
Defrost Control
The defrost control board includes the combined functions
oftime/temperaturedefrost control, defrost relay,diagnostic
LEDS and terminal strip for field wiring connections (See
Figure 14).
The control provides automatic switching from normal
heating operation to defrost mode and back. During the
compressorcycle(callfordefrost), the control accumulates
compressor run time at 30, 60, 90 minute field adjustable
intervals. If the defrost thermostat is closed when the
selectedcompressor runtimeinterval ends, thedefrostrelay
is energized and the defrost begins.
Page 18
Figure 14
Defrost Interval
Timing Pins
Diagnostic LEDs
24V TerminalStrip
Connections
High Pressure Switch
(optional)
Defrost Thermostat
Reversing Valve
Compressor Delay Pins
Test Pins
K1 Relay
K2 Relay
FAN
DS1
L
24V
P2
P5
O-OUT
DF
Y1-OUT
HI-PS
U1 U2
DS2
K3 Relay
P6
TST PS DF C R O Y1
C5
LO-PS
C2
P1
30
60
90
TEST
W1
C
L
R
Y1
O
Low Pressure Switch
(optional)
Defrost Control Board

506470-01 Issue 1007
Defrost Control Timing Pins
Each timing pin selection provides a different accumulated
compressorrun time periodduringone thermostatruncycle.
Thistime periodmustoccurbeforea defrostcycleis initiated.
The defrost interval can be adjusted to 30 (T1), 60 (T2), or
90 (T3) minutes. The defrost timing jumper is factory
installedto providea60minute defrost interval. If the timing
selector jumper is not in place, the control defaults to a 90
minute defrost interval. The maximum defrost period is 14
minutes and cannot be adjusted.
Atest option is provided for troubleshooting. The test mode
may be started any time the unit is in the heating mode and
the defrost thermostat is closed or jumpered. If the jumper
is in the TEST position at power up, the control will ignore
the test pins. When the jumper is placed across the TEST
pins for 2 seconds, the control will enter the defrost mode.
Ifthe jumperis removedbeforeanadditional5secondperiod
has elapsed (7 seconds total), the unit will remain in defrost
modeuntilthedefrostthermostat opens or 14 minutes have
passed. Ifthejumperis notremoveduntil aftertheadditional
5 second period has elapsed, the defrost will terminate and
the test option will not function again until the jumper is
removed and reapplied.
Compressor Delay
The defrost board has a field-selectable function to reduce
occasionalsoundsthat may occur while the unitiscyclingin
andoutofthedefrostmode. Thecompressorwillbecycled
offfor30secondsgoing in andoutofthe defrost modewhen
the compressor delay jumper is removed.
NOTE: The 30-second “off” cycle is not functional when
jumpering the TEST pins.
Time Delay
The timed-off delay is 5 minutes long. The delay helps to
protectthecompressorfrom short cycling in case the power
to the unit is interrupted or a pressure switch opens. The
delayisbypassedby placing the timer select jumper across
the TEST pins for 0.5 seconds.
Pressure Switch Circuit
The defrost control includes two pressure switch circuits. A
high pressure switch is connected to the board’s HI-PS
terminals(See Figure 14). The low pressure, or loss-of-
charge pressure, switch is connected to the LPS terminals.
During a single demand cycle, the defrost control will lock
out the unit after the fifth time that the circuit is interrupted
byan pressure switchwiredto thecontrolboard. Inaddition,
thediagnosticLEDswillindicatealocked-outpressureswitch
after the fifth occurrence of an open pressure switch (See
Table 9). The unit will remain
locked out until power to the board is interrupted, then re-
established, or until the jumper is applied to the TEST pins
for 0.5 seconds.
NOTE: The defrost control board ignores input from the
low pressure switch terminals as follows:
•During the TEST mode
•During the defrost cycle
•During the 90 seconds start-up period
• For the first 90 seconds each time the reversing
valve switches heat/cool modes
If the TEST pins are jumpered and the 5 minute delay is
being bypassed, the LO-PS terminal signal is not
ignored during the 90-second start-up period.
Diagnostic LEDs
Thedefrost board usestwoLEDs for diagnostics. TheLEDs
flash a specific sequence according to the condition as
shown in Table 9.
Page 19
Table 9
Defrost Control Board
Diagnostic LEDs

506470-01 Issue 1007
System Diagnostic Module
4HP18LT units contain a diagnostic module for
troubleshoutingheatpumpsystemfailures. Bymonitoring
and analyzing data from the compressor and thermostat
demand, the module can accurately detect the cause of
electrical and system related failure without any sensors.
If a system problem occurs, a flashing LED indicator
communicates the failure code.
LED Description
POWER LED (Green) indicates voltage is present at the
power connection of the module.
ALERT LED (Yellow) communicates an abnormal system
condition through a unique flash code. The ALERT LED
willflashanumberof times consecutively, pause,and then
repeat the process. The number of consecutive flashes
correlates to a paticular abnormal condition.
TRIP LED (Red) indicates there is a demand signal from
thethermostatbutnocurrent to thecompressoris detected
by the module. The TRIP LED typically indicates the
compressor protector is open or may indicate missing
supply power to the compressor.
Interpreting the Diagnostic LEDs
Whenan abnormal systemconditionoccurs, the diagnostic
nodule displays the appropriateALERT and/orTRIP LED.
The yellow ALERT LED will flash a number of times
consecutively, pause, and then repeat the process. To
identify a slash code number, count the number of
consecutiveflashes. RefertoTable10below and Table11
on page 20 for information on the flash codes.
Page 20
Table 10
Flash Codes